Superimposition of a crystal structure over EM images

電顕画像への結晶構造のあてはめ

松本 淳; 高木 淳一*; 岩崎 憲治*

Matsumoto, Atsushi; Takagi, Junichi*; Iwasaki, Kenji*

We developed a method for comparing 2-D images to a pool of deformed atomic structures that reduces the susceptibility of subjective interpretation and is more expeditious than 3-D analysis. Firstly, we used normal mode analysis (NMA) in the context of an elastic network model to prepare a pool of deformed structures from coarse-grain (CG) structural models. Then, small deformations were applied to the model along low frequency normal modes. Both NMA and deformation were performed iteratively to build many different deformed atomic structures. 2-D images were then compared to these structures to objectively locate their model of best fit. The fitting-search is performed as a rigid body fitting, which works effectively for very noisy raw images as well as for molecules with a large conformational change. Our most representative example of this hybrid approach of using 2-D EM images and crystal structures has been the study of the integrin cell-adhesion molecules. Our hybrid method has allowed the investigation of the conformationally flexible integrins.